The present invention relates to a magnetic particle-containing member for preventing an image-flow of a photosensitive member provided with an amorphous carbon layer formed on an uppermost surface thereof.
Since the discovery of the Carlson's method, the field, to which an electrophotography is applied, has continued to make a remarkable progress and various kinds of material have been developed to be practically used also for an electrophotographic photosensitive member.
The photosensitive member serves to form an electrostatic latent image corresponding to a desired image on a surface thereof by utilizing a photoconductive function.
Various kinds of materials used in the photosensitive member have been proposed. One of them is a plasma-polymerized layer of organic compounds. The organic plasma-polymerized layer [hereinafter referred to as "amorphous carbon layer" (a-C layer)] is mainly composed of an amorphous carbon layer which is originally hard. Therefore, the amorphous carbon layer is used as a surface protective layer for various kinds of photosensitive members. The amorphous carbon layer exhibits an electric conductivity by suitably selecting manufacturing conditions, additives and the like and thus it is used as a charge-transporting layer in a photosensitive member of laminate structure comprising a charge-generating layer and the charge-transporting layer in some cases.
The photosensitive member used in the copying machine is exposed to an active gaseous atmosphere, such as ions, ozone and NO.sub.x, generated from a charger during a charging process.
These active gases are adhered to a surface of the photosensitive member to influence characteristics of the photosensitive member adversely.
The amorphous carbon layer has a property of adsorbing these active gases. According to knowledges of the present inventors, the adsorption property is as follows:
When an affinity of an organic photosensitive member (OPC), the surface of which is formed of a mixture of a resin and a charge-transporting agent, to water is compared with that of a photosensitive member (a-C/OPC) having a surface protective layer (a-C) on the organic photosensitive member (OPC) to water by measuring a water contact angle, both the OPC and the a-C/OPC exhibited a water contact angle of 85.degree. to 90.degree. in the beginning. The OPC, however, exhibits the water contact angle of about 60.degree. while the a-C/OPC exhibits the water contact angle of about 25.degree. after charging and exposure is repeated about 20000 times.
This fact indicates that the amorphous carbon layer can very easily adsorb the active gases generated in a charging process.
On the other hand, the photosensitive member exhibiting the water contact angle of 40.degree. or less adsorbs a moisture in an atmosphere on the surface thereof to reduce a surface resistance. In this case, a so-called image-flow is observed when the photosensitive member is used under a high-temperature and high-humidity environment, for example 35.degree. C. and 85%.
In order to prevent such an image-flow, it is required to remove the active gases adsorbed on the surface every time when charged.
A technique for preventing the image-flow is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 62-34182 and the like. According to this technique, an amorphous silicon surface layer is slidingly rubbed with a toner or a blade made of a polyester resin to remove the active gases adsorbed on a surface thereof.
However, a gas adsorptive capacity of the amorphous carbon layer is remarkably higher than that of amorphous silicon, so that the surface of the amorphous carbon layer can not be sufficiently cleaned by the above described measure.